Flexible continuous cathode contact circuit for electrolytic plating of C4, TAB microbumps, and ultra large scale interconnects

ABSTRACT

A cathode contact device is provided for providing particle deposition from an anode source onto a target surface of a working piece. The working piece has a first electrically conductive continuous contact surrounding the target surface. The cathode contact device includes a second electrically conductive continuous contact adapted for frictionally contacting the first contact along a continuous path located on the first contact. The second contact further has an inner periphery defining an aperture for passing therethrough the particles onto the target surface. Additionally, the cathode contact device includes a circuit for electrically coupling the second contact to an electrical current supply.

This is a continuation of application Ser. No. 08/534,489, filed Sep.27, 1995, U.S. Pat. No. 5,807,469.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to the field of electroplating. Morespecifically, the present invention relates to an apparatus and a methodfor improving the process of electroplating of controlled collapse chipconnection (C4) microbumps, of tape automated bonding (TAB) microbumps,and of integrated circuit interconnects.

2. Related Art

Typically, integrated circuits are assembled by using the standard"wirebond" integrated circuit method which will be explained inconjunction with FIGS. 1a-1d. FIG. 1a shows a wafer 10 with dice 12 laidout in horizontal and vertical rows. A die can be singled out, as shownin FIG. 1b, and bonded into a Pin Grid Array package (PGA) 14 shown inFIG. 1c. As one can see from this figure, first the die 12 is positionedface up within a recess 17 made onto the top surface 16 of the PGA 14.Then the die is bonded to the PGA 14 by means of the wirebond pads 18.The wirebond pads 18 are also connected to various functional blocks ofthe die via conductors (not shown). Typically, up to 600 wirebond padsare positioned around the periphery of the die for making connectionswith the package. A wirebonder is used to wirebond the die, via thewirebond pads 18 to the wirebond pads 19 positioned onto the top surface16 of the PGA 14. The wires are looped up and over to the correspondingpads on the package as shown in FIG. 1d. One drawback of this method isthat the routing of conductors, from the functional blocks of the die tothe peripheral wirebond pads 18, increases signal propagation delays dueto the high impedance of the conductors.

A more recent technology called controlled collapse chip connection("C4") has emerged in the field of integrated circuit assembly.According to this method, the chip is positioned face down in thepackage, instead of face up. The die is then connected to the packagevia a plurality of solder bumps which are soldered to both the die andthe package. The connections between the package and the die are madestraight down into the package, as opposed to the connections in theconventional wirebond technology where the connections were made byrouting conductors or wires to the peripheral wirebond pads, and thenlooping wires up and over to the package. Due to the shorter signal pathfrom the die to the package, this method provides an improvement overthe old method with respect to the parasitic impedances of theconductors.

According to one method for depositing solder bumps onto a wafer, amolybdenum mask 30 is overlaid onto the wafer 10 and then aligned to theinput/output of each die 12 as shown in FIG. 2. The molybdenum mask hasopenings 32 at locations corresponding to the projected signalconnections on the die. The wafer 10 and the overlaid mask 30 areinserted into a vacuum chamber and exposed to physical vapor deposition.A compound such as lead and tin, for example, is heated until it melts,evaporates inside the vacuum chamber, and deposits through openings 32onto the wafer, thereby forming bumps. Once the compound is deposited,the molybdenum mask is torn off the wafer. The C4 bumps remain on thewafer at the desired locations corresponding to the respective openingsin the mask thereby defining the desired microbump pattern in themolybdenum mask. The problem with this process is that a lot of thematerial is wasted during the deposition. Almost 90-98% of the materialis deposited on the vacuum chamber's walls instead of being depositedonto the wafer.

A more advantageous method is electroplating solder onto the wafer. Thismethod involves initially metalizing the surface of the wafer therebyforming a conductive layer across the wafer. The next step is depositinga photoresistive mask which defines a predetermined bump patterns, uponthe surface of the conductive layer. The photoresistive materialelectrically insulates the metal layer except for the openings throughthe photoresist where bumps are to be plated. The following step isplating the bumps with an alloy of lead and tin. The bumps build up in apredetermined bump pattern, each bump having a desired final height. Thenext step is stripping the photoresistive material and also strippingthe portions of the conductive layer which do not have bumps platedthereon so that the bumps will not be short-circuited.

The system used for the above-described electroplating process isconfigured utilizing a cup which contains the electrolyte and holds thewafer in place during the electroplating process. Electrolytic platingrequires, among other things, an electrolyte which contains lead and tinin an ionic suspension, for example. Other metals however, depending onthe specific application, can be used in the ionic suspension.Furthermore, electrolytic plating requires electrical contacts onto thewafer such that a negative charge will be distributed onto theconductive metal layer of the wafer. The negative charge flowing ontothe wafer combines with positive ions from the electrolytic solution,through a reduction process, thereby causing the lead to be depositedonto the wafer in the form of microbumps positioned onto the waferaccording to a predetermined microbump pattern. Typically, there are twotypes of currents which flow onto the wafer-cathode current and anodecurrent. The cathode current is provided by the cathode along thesurface of the wafer. The anode current, provided by the anode assembly,flows in a direction substantially transversal to the plane of the wafertowards the wafer to be plated.

The above-described method, however, suffers from several disadvantages.One such disadvantage is non-uniform cathode current flowing onto thecathode surface of the wafer. The non-uniform cathode current causesnon-uniformity in the anode current which in turn causes the microbumpsformed onto the wafer to display non-uniformity across the wafer. Thenon-uniform cathode current flowing onto the wafer is caused, mostly, bythe fact that prior art cathode contacts were connected to the wafer atonly a discrete number of points located at the periphery of the wafer.

Non-uniform bumps can cause several problems. For example, if the chiphas bumps that are very small and bumps that are very large, the diewill be tilted upon its assembly onto the package. The lack ofuniformity in the bump pattern also causes open circuits due to the factthat not all microbumps are connected to the pads of the package. Yetanother problem occurs where bumps are formed so close to each othercausing a short circuit. This type of problem is also known as bridgingbumps.

Furthermore, non-uniform distribution of negative charge onto the targetsurface can affect the deposition of metallic particles in cases otherthan microbumps electroplating. For example, integrated circuitinterconnects are also plated onto silicon wafers. Non-uniformity of thecathode current can cause non-uniform thickness of the platedinterconnect. This, in turn, can cause undesirable effects such aselectro-migration.

Furthermore, some electroplating methods require that the cathodecontact, which is mounted on top of the cup, is easily removable once itis used up. However, removal of the cathode contact can be verydifficult since the cathode contact will stick to the rim of the cupholding the cathode contact due to lead tin, or other metal, depositedbetween the cathode contact and the rim of the cup.

Consequently, a different type of configuration for the cathode contactis desirable such that the anode current flowing across the wafer willbe uniformly distributed across the surface of the wafer. Moreover, itis desirable to have a cathode contact which is protected from particledeposition thereon. Furthermore, it is desirable to have a cathodecontact which is easily removable once this contact needs to bereplaced. Also, it is desirable to have a cathode contact which providesa resilient sealing against the photoresist layer of the wafer--therebyprotecting, from deposition during plating, the exposed conductive metalcontact located at the edge of the wafer. It is also desirable that thecathode contact be very thin in order to minimize the obstruction ofsmooth flow of the electrolyte at the periphery of the wafer. Also, itis desirable to have a cathode contact which is easily and preciselypositioned onto the electroplating cup relative to a conductive contactof the wafer located at the periphery of the wafer.

BRIEF SUMMARY OF THE INVENTION

An apparatus and method are disclosed for overcoming the disadvantagesand limitations associated with prior art cathode contact devices. Suchdisadvantages and limitations include, but are not limited to:non-uniform microbump or interconnect deposition created by discretecathode contacts; undesired metallic deposition onto the surface of thecathode; and, difficulty in removing the cathode contact from the waferonce the cathode contact needs to be replaced.

The present invention provides a cathode device for providing particledeposition onto a target surface of a working piece. The particles to bedeposited onto the target surface are driven by an electrical fieldcreated by the cathode device and an anode. The working piece generallyhas a first electrically conductive continuous contact surrounding thetarget surface of the working piece. The cathode device includes asecond electrically conductive continuous contact adapted forfrictionally contacting the first contact along a continuous pathlocated on the first contact. The second contact further has an innerperiphery defining an aperture for passing therethrough the particlesonto the target surface of the working piece. Additionally, the cathodedevice is provided with a circuit for electrically coupling the secondcontact to an electrical current supply.

According to one embodiment of the present invention, it is provided acathode contact device for electroplating microbumps or interconnectsonto a substantially circular target surface of a semiconductor wafer,the semiconductor wafer having a first substantially annularelectrically conductive contact surrounding the target surface, themicrobumps or interconnects being formed by deposition of metallic ionsonto the target surface at predetermined microbump or interconnectlocations. The ions are driven by an electric field created by saidcathode device and an anode upon coupling the cathode contact device andthe anode to an electric current supply. The cathode contact deviceincludes a second substantially annular electrically conductivecontinuous contact, substantially similar with the first contact. Thesecond contact is adapted to frictionally engage the first contact alonga continuous path located on the first contact. The second contact has asubstantially circular inner periphery defining an aperture for passingthe metallic ions onto the target surface. The site of the aperture issubstantially identical with the circular target surface. The cathodecontact device further has a circuit for supplying cathode current fromthe electric current supply to the second contact.

In another embodiment, a cathode contact device is provided for particledeposition onto a target surface of a working piece. The working piecehas a first electrically conductive continuous contact surrounding thetarget surface. The cathode contact device comprises a flexible metalclad laminate having a flexible electrically conductive continuouscontact adapted for frictionally contacting the first contact along acontinuous path located on the first contact. The second contact furtherhas an inner periphery defining an aperture for passing therethrough theparticles onto the target surface. The cathode contact device furtherhas a circuit for electrically coupling the second contact to a currentsupply.

The present invention also provides a method for providing uniformparticle deposition from an anode source onto an electrically conductivetarget surface of a working piece. The method comprises the steps of (a)depositing by photolithography, a layer of photoresist onto the targetsurface, wherein selected areas of the target surface are covered by thephotoresist, and non-selected areas of the target surface are notcovered by the photoresist according to a predetermined particledeposition pattern; (b) removing, by etching, a portion of saidphotoresist located at the periphery of said layer of photoresist,thereby providing a first electrically conductive continuous contactaround the target surface; (c) providing a source of particles; (d)providing a cathode contact device having a second electricallyconductive continues contact adapted for frictionally contacting thefirst contact along the continues path located on the first contact, thesecond contact further having an inner periphery defining an aperturefor passing therethrough the particles onto the target surface; (e)providing an anode for creating an electrical field between said anodeand said cathode thereby driving said particles from said source ofparticles; (f) providing a circuit for electrically coupling the secondcontact to an electrical current supply; (g) mounting the cathodecontact device onto the periphery of a working structure; (h) laying theworking piece upon the cathode contact device whereby the first andsecond contacts are frictionally engaged around a continuous pathlocated on the first contact; (i) coupling the second contact and theanode to an electrical current supply.

BRIEF DESCRIPTION OF THE DRAWINGS

The features, aspects, and advantages of the present invention willbecome more fully apparent from the following detailed description,appended claims, and accompanying drawings in which:

FIG. 1a-1d show different aspects of a conventional wirebond assembly ofa die onto a package, in which

FIG. 1a shows a wafer with a plurality of dies;

FIG. 1b shows a single die having a plurality of wire bond pads;

FIG. 1c shows a die and a PGA package before mounting the die on to thePGA package;

FIG. 1d shows a die mounted onto the PGA package.

FIG. 2 illustrates a flip chip mask with a wafer according to the priorart C4 method.

FIG. 3 illustrates an electroplating assembly with a cathode contactdevice mounted therein.

FIG. 4 illustrates a view of a wafer and the cathode contact deviceaccording to the present invention.

FIG. 5 illustrates a top view of the continuous cathode contact deviceaccording to the present invention.

FIG. 6 shows a top view of the continuous contact device mounted into anelectroplating cup.

FIG. 7 illustrates a cross-section of the annular portion of a laminatedclad incorporating the cathode contact device according to the presentinvention.

FIG. 8 illustrates a longitudinal cross-section of an arm for connectingthe cathode contact device to an electrical current supply.

FIG. 9 illustrates a cross-sectional view of a cathode contact devicemounted onto a wafer.

FIG. 10 illustrates an alternative embodiment of a discrete flexiblecathode contact device according to the present invention.

DETAILED DESCRIPTION OF THE INVENTION

In the following description, numerous specific details are set forth toprovide a thorough understanding of the present invention. However, onehaving ordinary skills in the art may be able to practice the inventionwithout the specific details. In some instances, well-known circuits,structures and techniques have not been shown in detail not tounnecessarily obscure the present invention.

The present invention provides for a cathode contact device thatgenerates a uniform current distribution over the entire surface of awafer. In a preferred but non-limiting embodiment according to thepresent invention, the cathode contact is substantially continuoushaving a substantially annular surface surrounding the wafer. By using acontinuous cathode contact, the negative charge current flowing onto thewafer can be uniformly distributed over the surface of the wafer causingin turn the anode current to be uniformly distributed across the surfaceof the wafer.

FIG. 3 shows a cross-sectional view taken across a longitudinal axis 1of an electroplating assembly according to the present invention. Theelectroplating assembly according to the present invention includes acup-shaped container 2 having an inner wall 4 defining an inner volume.The cup-shaped container 2 further has an outer wall 6. Mounted at alower end of the container is a pipe 8 extending upwardly through theinner volume of the cup-shaped container. The upper part of pipe 8 issurrounded by a seal 10 located between the lower end part of the cupand the outer wall 7 of the pipe 8. The pipe 8 is inserted, at a lowerend, into a vessel (not shown) having an electrolytic solution withmetallic ions. The vessel further can be provided with a pump forpumping the metallic ions upwardly through pipe 8 and for expellingthese ions via the opening 9, located at the upper end of tube 8, intothe volume defined by the inner wall 4 of the cup.

The assembly shown in FIG. 3 is adapted to electroplate a target surface18 of the working piece 16. Target surface 18 is the surface which needsto be electroplated for the purpose of generating microbumps or otherconductive structures such as interconnects, for example, onto the wafer16. In FIG. 3, target surface 18 is the surface of the wafer which isoriented downwardly, facing thus the flow of metallic ions. Furthermore,in this particular embodiment, working piece 16 has a substantiallycircular configuration. However, the assembly, according to the presentinvention, is not limited to electroplating circular working pieces.Surfaces other than circular can be electroplated too.

The following discussion will refer to working piece 16 as a siliconwafer, although the scope of the present invention is not limited tosilicon wafers. The silicon wafer 16 is mounted on top of asubstantially annular cathode contact device 20 according to the presentinvention. The wafer 16 has an electrically conductive continuouscontact (not shown) at the periphery of the target surface 18. Thiscontact defines the contour of the substantially circular targetsurface. In this particular embodiment, the contact of the wafer issubstantially annular. The cathode contact device 20 includes anelectrically conductive continuous contact (not shown). The electricallyconductive continuous contact of the cathode contact device 20, in thisparticular embodiment, is substantially annular. The continuous contactof cathode contact device 20 is adapted for frictionally contacting theelectrically conductive continuous contact of the work piece 16 along acontinuous path. The continuous path, along which the frictionalengagement is provided, serves the purpose of creating a continuouselectrical connection between the electrical current supply 24 and theconductive layer of silicon wafer 16, when the anode and cathode contactdevice illustrated in this figure are operatively connected toelectrical current supply 24.

An anode 12 is positioned, within the inner electroplating cup wall 4,substantially transversely with respect to longitudinal axis 1. Inoperation, the cathode contact device 20 is connected to the negativepole of the current source 24 while the anode 12 is connected to thepositive pole of current source 24.

The cup 2 also includes a substantially annular base 3. This basesupports the cathode contact device 20. The cup 2 further has a gap 23through which metallic ions that are not deposited onto the targetsurface 18 are evacuated.

Cathode contact device 20 additionally has at least an electricallyconductive arm 28 outwardly extending from the electrically conductivecontact of the cathode. In this particular embodiment electricallyconductive arms 28 are made of a flexible material for the purpose ofconnecting the cathode device to the screws 21. From screws 21electrically conductive wires 25 are connected to the electrical currentsupply 24. A balloon 26 is positioned at the upper part of the assemblyfor holding the wafer in place upon the inflation of this balloon.

FIG. 4 shows a view of the wafer 16 and the cathode contact device,according to the present invention. According to this configuration whenthe center 0 of the cathode contact device 20 is concentrically alignedwith the center 00 of the wafer 16, and the wafer 16 is frictionallysuperimposed over the cathode contact device 20, the electricallyconductive continuous contact 202 can frictionally contact the topsurface 19, of electrically conductive continuous contact 17 of thewafer, along a continuous path (not shown). Consequently, uponconnecting the cathode device 20 and the anode (not shown) to anelectrical current source, a substantially uniform flow of negativecharge over target surface 18 of the wafer will result. Accordingly, acorresponding uniform electric field created between the anode and thecathode will act upon the metallic ions which will thus be uniformlydistributed across the target surface 18. Therefore, a substantiallyuniform deposition of the desired metal onto a predetermined microbumppattern or interconnect pattern will result.

FIG. 5 illustrates a top view of the continuous cathode device 20according to the present invention. As one can see, the cathode device20, in this particular embodiment, has a substantially annular shape.Cathode device 20 includes an electrically conductive continuous contact202. Contact 202 has a top surface 203 adapted for frictionallycontacting the continuous electrically conductive contact of targetsurface 18 of FIGS. 3 and 4.

The contact 202 has a shape and a size substantially identical with theelectrically conductive continuous contact of the wafer. This is toensure that upon mounting the wafer 16 on top of cathode contact device20, contact 202 frictionally contacts the electrically conductivecontinuous contact of wafer 16 along a continuous path located on theelectrically conductive continuous contact 17 of wafer 16. However, theshape and size of the electrically conductive contact 202 are notlimited to the shape and the size of the electrically conductivecontinuous contact 17 of wafer 16. The contact 202 could have adifferent shape and/or size as long as its top surface 203 frictionallycontacts the contact 17 of wafer 16 along a continuous path located onthe continuous contact of the wafer, when the wafer and the cathodedevice 20 are aligned and contact each other. For example, the contact202 could have a disk shape, as opposed to annular shape, equal orgreater than the target surface of the wafer. In this case, the cathodedevice 20 could be positioned on top of wafer 16 as opposed to beneathwafer 16. Wafer 16, in this case, would have its electrically conductivecontinuous contact running along the back surface of the wafer.

In another embodiment, the electrically conductive continuous contact ofwafer 16 could be positioned around the circular side 37 of wafer 16shown in FIG. 4. In this case, the cathode contact device 20 could beadapted to continuously frictionally engage wafer 16 around the circularside 37. In this case, the desired continuous electrical contact of thecathode contact device with the electrically conductive contact of thewafer would be made around the circular side 37.

The cathode contact device 20 further has a circuit for coupling theelectrically conductive body to the electrical current supply (notshown). In this particular embodiment, the circuit for coupling theelectrically conductive contact 202 to the electrical current supplyincludes one or more arms 214 outwardly extending from contact 202. Inthis particular embodiment, arms 214 are made integrally with contact202. Arms 214 have a free end 218 provided with an aperture 202 forconnecting the cathode contact 202 to the electrical current supply.

Additionally, the cathode contact device 20 has a substantially circularinner periphery 210 and a substantially circular outer periphery 212. Asone can see from this figure, the inner periphery 210 and the outerperiphery 212 define the boundaries of cathode device 220. The innerperiphery 210 defines the area of the target surface which will beelectroplated. As such, the shape of the inner periphery is not limitedcircular, but it can have any other shape corresponding to the desiredshape of the surface to be electroplated. Similarly, the outer periphery212 is not limited to circular but can also have other shapes.

For example, the shape of the outer periphery may be constrained by arecess placed onto the rim (top surface) of the cup upon which thecathode is mounted.

FIG. 6 shows the cathode contact device 20 of the present inventionoverlaid on the top surface of cup 2. The continuous cathode contactdevice is held in place, in cup 2, by a recess machined in the topsurface of the cup. This recess matches the inner and outer periphery ofthe cathode contact device such that the cathode contact device is heldin a substantially fixed position with respect to the cup.

FIG. 7 shows a cross-section of the annular part of the cathode contactdevice 20 having annular dielectric layer 226 bonded to contact 202thereby forming a clad laminate. When the cathode contact device ismounted on the top surface of cup 2, of the electroplating assemblyillustrated in FIG. 6, the electrically conductive contact 202 will beshielded from ionic contact by dielectric surface 226 which prevents thedeposition of metallic ions onto this contact. Generally, the dielectriclayer 226 is laminated to the electrically conductive contact 202 by aprocess of photolithography.

The electrically conductive arms 214 can be equally clad into a laminatehaving two layers of dielectric 230 and 232 sealably enclosing arms 214in between as shown in FIG. 8. In such way ion deposition onto thesurface of the arms 214 is prevented equally.

The dielectric layer 226 substantially prevents ionic deposition ontothe continuous electrically conductive contact 202 of the wafer, as onecan see in FIG. 9 which shows a cross-sectional view of the couplingbetween the cathode contact and the periphery of the wafer 16. This isachieved by sealing the internal portion 228, of the dielectric layer226, against the periphery of the photoresist layer 23 coated onto thetarget surface. The dielectric layer can be made of polyamide or anyother type of dielectric material which is resilient to compressionagainst the photoresistive surface 23. FIG. 9 also shows the contact 202frictionally engaged with the conductive contact 17 of the wafer therebyproviding an electric path for the flow of negative electric charge fromthe current supply onto the target surface of the wafer.

The electrically conductive contact 202 and the dielectric layer 226 canbe made of flexible materials bonded as a flexible laminate clad. Thisfeature offers the capability of easily removing the cathode when suchcathode is used up due to exposure to electrolyte acids and wear imposedby multiple wafer processing. Because the cathode contact device has tobe fitted through small spaces and, consequently, at times it needs tobend, a flexible contact such as the contact according to the presentinvention overcomes this mounting problem. Similarly, flexible arms 214of the flexible cathode contact device according to the presentinvention can be slipped through narrow slots in the side of the cup,and then routed out to the power supply much like a wire. Accordingly,the cathode contact device can be easily replaced without incurring thetime penalty that would otherwise be required to disassemble the entireelectroplating assembly.

The flexible cathode contact device according to the present inventionprovides an additional advantage. As one can see in FIG. 3, a certainamount of metallic particles are evacuated through the gap 23 afterbeing flown towards the target surface 18. It is desirable that the flowof metallic ions in the vicinity of the periphery of the wafer, close tothe gaps 23, is not obstructed. An obstruction in the path of theseparticles could disturb the smooth flow of these particles, therebycausing turbulences which affect the deposition of metal at theperiphery of the wafer. As one can see in FIG. 3, the base 3 forms, to acertain extent, an obstruction in the path of ions flowing out towardsgap 23. The cathode contact device 20 inserted into the electroplatingassembly additionally contributes to the obstruction of ions. It is thusdesirable to have a cathode contact device with a very low thicknesssuch that the obstruction posed by this cathode contact device isminimized. The cathode contact device, according to the presentinvention, substantially minimizes the effect of its obstruction in thepath of metallic ions by having a low thickness.

FIG. 10 illustrates a different embodiment of the present inventionwherein the cathode contact device includes a plurality of flexible tabswhich connect the power supply to the electrically conductive contact ofthe wafer at a discrete number of points. For example certain types ofelectroplating applications such as gold electroplating require a lowercathode current. Very often in such applications, the target surface tobe electroplated is relatively small with respect to the cathodecontact. In this situation the cathode contact has to be preciselypositioned with respect to the target surface. The present inventionprovides for a mechanism for installing the discrete cathode contacttabs onto discrete recesses positioned onto the top surface of the cup.As one can see in FIG. 10, tab 314 has a first portion 316 with an end318 for coupling to an electrical current supply. Tab 314 has a secondportion 318 integral with the first portion. The second portion has end322, for frictionally contacting the electrical conductive contact ofthe target surface (not shown). The first portion has a width largerthen the width of the second portion. The shoulder 320 is formed at thejunction of those portions. This shoulder acts as a stopper. When thecathode contact device 20 is installed within the cup 2, illustrated inFIG. 10, the shoulder 320 rests against the outside periphery of thecup, thus, providing the means for positioning the contact preciselywithin the recess of the top surface of the cup.

In the foregoing specification, the invention has been described withreference to specific embodiments thereof. The specification anddrawings are accordingly, to be regarded in an illustrative rather thana restrictive sense. It will however be evident that variousmodifications and changes can be made thereto without departing from thebroader spirit and scope of the invention as set forth in the appendedclaims.

What is claimed is:
 1. A cathode device to contact a working piece, saidcathode device comprising:a first electrically conductive continuouscontact to frictionally contact a second electrically conductivecontinuous contact, of said working piece, along a continuous pathlocated on said second contact, said first contact further having aninner periphery defining an aperture; and at least one electricallyconductive arm integral with said first contact and extending from saidfirst contact.
 2. The device of claim 1 wherein said first continuouscontact is substantially annular.
 3. The device of claim 1 wherein saidfirst and second contacts have substantially identical shapes.
 4. Thedevice of claim 1 wherein said first and second contacts havesubstantially identical sizes.
 5. A cathode contact device to contact aworking piece, said cathode device comprising:a first flexible cladlaminate having a first electrically conductive continuous contact tofrictionally contact a second electrically conductive continuouscontact, of said working piece, along a continuous path located on saidsecond contact, said first flexible clad laminate further having aninner periphery defining an aperture said first flexible clad laminatehaving an insulating flexible layer bonded to said first electricallyconductive continuous contact; and at least one electrically conductivearm integral with said first contact and extending from said firstcontact.
 6. The device recited in claim 5 wherein said insulating layercomprises polyamide.
 7. The device of claim 5 wherein said firstcontinuous contact is substantially annular.
 8. The device of claim 5wherein said first and second contacts have substantially identicalshapes.
 9. The device of claim 5 wherein said first and second contactshave substantially identical sizes.
 10. The device recited in claim 5wherein said insulating layer is substantially annular.
 11. The devicerecited in claim 5 wherein said insulating flexible layer has asubstantially annular resilient sealing surface extending radiallyinwardly from said first contact.
 12. The device recited in claim 5wherein a combined thickness of said first electrically conductivecontinuous contact and said insulating flexible layer is approximately0.12 mm.
 13. A cathode contact device to contact a working piece, saidcathode contact device comprising:at least one electrically conductivetab having a first portion, with a first end to couple to an electricalcurrent supply, and a second portion, integral with said first portion,said second portion having a second end, opposite from said first end,to frictionally contact said electrical conductive contact of the targetsurface, said first and second portions have respectively, first andsecond widths, said first width being greater than the second width, ashoulder is formed at the junction of said first and second portions.14. The device of claim 13 wherein said shoulder is adapted to engagewith a cup supporting said tab, whereby upon frictional engagementbetween said shoulder and a side of said cup, said second end of the tabis substantially aligned with said electrically conductive contact ofsaid target surface.
 15. The device of claim 13 wherein said circuit forcoupling said flexible electrically conductive continuous contact tosaid electric current supply includes a second flexible clad laminatehaving a flexible electrically conductive layer integral with saidcontact and sealably bonded between a first and a second flexibleinsulating layers.
 16. A cathode device to contact a working piece, saidcathode device comprising;a substantially annular first electricallyconductive continuous contact to frictionally contact a secondelectrically continuous contact, of said working piece, along acontinuous path located on said second contact, said first contactfurther having an inner periphery defining an aperture; and at least oneelectrically conductive arm integral with said first contact andextending from said first contact.
 17. A cathode contact device tocontact a working piece, said cathode device comprising;a substantiallyannular first clad laminate having a first electrically conductivecontinuous contact to frictionally contact a second electricallyconductive continuous contact, of said working piece, along a continuouspath located on said second contact, said first clad laminate furtherhaving an inner periphery defining an aperture said first clad laminatehaving an insulating layer bonded to said first electrically conductivecontinuous contact; and at least one electrically conductive armintegral with said first contact and extending from said first contact.18. A cathode contact device to contact a working piece, said cathodedevice comprising:a first clad laminate having a first electricallyconductive continuous contact to frictionally contact a secondelectrically conductive continuous contact, of said working piece, alonga continuous path located on said second contact, said first cladlaminate further having an inner periphery defining an aperture, saidfirst clad laminate having an insulating layer, bonded to said firstelectrically conductive continuous contact, said insulating layer havinga resilient sealing surface extending radially inwardly from said firstcontact configured to sealably contact a portion of said wafer.
 19. Thedevice recited in claim 18 wherein said resilient sealing surface issubstantially annular.
 20. The device of claim 18 wherein said portionof said wafer includes a dielectric material.
 21. The device of claim 18wherein said dielectric material includes photoresist.